Tilable Plasma in GIMP

There are two major products that came from Berkley: LSD and
BSD. We don't believe this to be a coincidence.

The GIMP image manipulation program offers a Plasma plug-in that renders
a cloudy smokey colored texture; unlike the nearby Solid Noise plug-in,
however, it does not offer the option to create a tileable pattern,
which can be useful as a base for textures for various uses.

Tileable plasma-like pattern

It is possibile to render a plain Plasma, and then make it tileable with
Filters -> Map -> Make Seamless but the results are not optimal with
this kind of hard-to-retouch images.
This tutorial present a different way to get a plasma-like texture
using tilable Solid Noise, basically generating the three RGB components
on independent layers.

This tutorial was originally published on my old website, and I've now
updated it to version 2.6 of GIMP.

Start a new image of the desidered size, with a white background. i
Create a new layer, you may call it "red", now use the
Filters -> Render -> Clouds -> Solid Noise... plug-in, check the
Tilable option and experiment with the rest; hit OK.
Now use Colours -> Colourify, select the red colour and hit OK.
Lastly, set the layer Mode to Difference: this will be the (inverted)
red component of the plasma.

First layer in GIMP

Colourify dialog

Repeat the same operations: create a new layer called "green",
render a Solid Noise with the same options, but a different Random Seed,
Colourify in green and set the layer as Difference:
you'll have the green inverted component.

Repeat once more: Colourify in blue for the blue inverted component
and you have a plasma pattern that can be tiled.

The finished image

The resulting texture

You may control the hues of the image by fiddling with the layers Opacity,
lowering the components you want to give prevalence to.
You can also invert the plasma by using a black background instead of
a white one, or give it a pattern with a greyscale background of your choice.